Blixt WalletLatest release: VARY ( 25th May 2022 ) 🔍 Last analysed 7th February 2022 . Not reproducible from source provided
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Try out searching for "lost bitcoins", "stole my money" or "scammers" together with the wallet's name, even if you think the wallet is generally trustworthy. For all the bigger wallets you will find accusations. Make sure you understand why they were made and if you are comfortable with the provider's reaction.
The Analysis ¶
Update 2022-02-07: This wallet recently reached 1000 downloads on Play Store, so now it’s time to see if it reproducible … See “Code and Reproducibility” below …
So we got a support request from somebody who put money into this lightning wallet and the channel instantly closed but days later he didn’t have his money back. Communications with the provider were not helpful neither.
The force-close transaction had a timelock as is normal in lightning - only weird thing was the timelock allows to spend after … 1987.
A lightning network force close is when one of the parties in a channel publishes a channel state without crafting a closing transaction with the counter party first. As this might happen in bad faith, the counter party is then supposed to have time to publish a punishment transaction, so this timelock should lay in the future, not some past at which there wasn’t any bitcoin yet. In summary, this transaction looks like a poorly implemented LN wallet. The transaction also had five outputs which is indicative of affecting more than two parties like in a custodial wallet?
On the Play Store description they claim (full description):
Blixt Wallet is a non-custodial open-source Bitcoin Lightning Wallet for Android with focus on usability and user experience, powered by lnd and Neutrino SPV.
The app is also available for iPhone only via testflight though.
Blixt Wallet’s main developer is Hampus Sjöberg who is well connected in Bitcoin Twitter.
According to the website:
Blixt Wallet is built as an MIT-licensed open-source project.
So next we would have to see if this app is reproducible. We will look into that once the app gained some more traction.
Code and Reproducibility
- Install Node, Yarn and Android Studio + Android SDK (including NDK)
- If needed, install an emulated android device inside Android Studio
- Download lnd binary from from the latest Blixt Wallet release and put it in
android/lndmobile. Alternatively build lnd for Android by following the steps in build-android-aar.md
- Get the tor sub-module:
git submodule update --init
- Install Node packages:
- Compile the Tor Android lib:
- Generate proto files:
To start the application:
There is two problems with this.
- There is no instructions to actually build the release file. Only instructions to start the debug version.
- We need an lnd binary. So while that can be built from source, there is no
pinning of the right version to build. Also the compilation of lnd requires
editing “line 47 of
We could maybe guess our way around these issues but this should really be better documented for smooth build reproduction.
Emanuel already tried to reproduce this app and his issue is still open. So while this app can be compiled from source, the compilation result differs from what he got from Google play. This app is currently not verifiable.
We could not verify that the provided code matches the binary!
As part of our Methodology, we ask:Is the published binary matching the published source code? If not, we tag it Unreproducible!
Published code doesn’t help much if it is not what the published binary was built from. That is why we try to reproduce the binary. We
- obtain the binary from the provider
- compile the published source code using the published build instructions into a binary
- compare the two binaries
- we might spend some time working around issues that are easy to work around
If this fails, we might search if other revisions match or if we can deduct the source of the mismatch but generally consider it on the provider to provide the correct source code and build instructions to reproduce the build, so we usually open a ticket in their code repository.
In any case, the result is a discrepancy between the binary we can create and the binary we can find for download and any discrepancy might leak your backup to the server on purpose or by accident.
As we cannot verify that the source provided is the source the binary was compiled from, this category is only slightly better than closed source but for now we have hope projects come around and fix verifiability issues.
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